When it is desired to slit a wide strip of sheet metal wound into a coil into a plurality of narrower strips each having a predetermined width, the wide strip is unwound from the coil and fed through a slitter which has a plurality of axially spaced sets of rotary cutting or shearing knives. The outer sets of knives are commonly used to trim the outer edges of the wide strip so that each narrow strip which is produced by the slitter has precisely parallel and smooth edges defining the desired uniform width. Frequently, the outer two scrap edge trimmings produced by the slitter are rewound into coils which are sold as scrap. However, there are a number of problems encountered in rewinding the narrow edge trimmings into scrap coils, such as, it is difficult to maintain substantially constant tension in each edge trimming in order to avoid breaking the edge trimming, and the removing of the scrap coils from the rewinder is time consuming and may be dangerous.
In view of the problems encountered when winding the continous scrap edge trimmings received from a slitter into corresponding coils, there have been a number of machines either constructed or proposed to cut or chop the scrap edge trimmings into small pieces which can be more conveniently handled and occupy significantly less space than bundles of wound edge trimmings. For example, three different forms of metal scrap choppers are disclosed in U.S. Pat. Nos. 3,060,778, 3,545,689 and 3,799,020. In any such scrap chopper, it is desirable for the chopper to be of compact, economical and dependable construction and to provide for independently feeding each edge trimming being received from the slitter with substantially constant tension to avoid breaking a strip. It is also desirable for a scrap chopper to be constructed to provide for convenient servicing in order to minimize down time of the slitter and chopper as well as minimize the cost of maintenance. The chopper should also provide for conveniently accommodating metal strips of various thicknesses, and the chopper should shear each metal strip with a scissor-like action in order to provide the cutting blades with maximum cutting life and to minimize the noise level at which the chopper operates.